Formulas to memorise** account for mid years tbc

Question 1

Newton’s second law (applied formula)

Answer 1

F = ma

force (N)
mass (kg)
acceleration (ms⁻²)

Question 2

Change in pressure

Answer 2

∆p = ϱg∆h

pressure (Pa/Nm⁻²)
density (kgm⁻³)
gravitational acceleration (ms⁻²)
height (m)

Question 3

Work done (in terms of pressure)

Answer 3

W = -p∆V

work (J/Nm)
pressure (Pa/Nm⁻²)
volume (m³)

Question 4

Kinetic energy

Answer 4

Eₖ = 1/2mv²

kinetic energy (J)
mass (kg)
velocity (ms⁻¹)

Question 5

Work done (in terms of force)

Answer 5

W = Fs
= Fr cosθ

work (J/Nm)
force (N)
displacement (m)

Question 6

Change in gravitational potential energy

Answer 6

∆GPE = mg∆h

gravitational potential energy (J)
mass (kg)
gravitational acceleration (ms⁻²)
height (m)

Question 7

Power (in terms of work)

Answer 7

P = W / t

power (Watt/Js⁻¹)
work done (J)
time (s)

Question 8

Power (with constant velocity)

Answer 8

P = Fv

power (Watt/Js⁻¹)
force (N)
velocity (ms⁻¹)

Question 9

Wave velocity

Answer 9

V = fλ

wave velocity (ms⁻¹)
frequency (Hz/s⁻¹)
wavelength (m)

Question 10

Charge

Answer 10

Q = It

charge (c)
current (A)
time (s)

Question 11

Potential difference (in terms of work)

Answer 11

V = W / Q

potential difference (volts)
work done (energy/J)
charge (c)

Question 12

Power (in terms of voltage)

Answer 12

P = VI

power (Watt/Js⁻¹)
potential difference (volts)
current (A)

Question 13

Power (in terms of resistance)

Answer 13

P = I²R

power (Watt/Js⁻¹)
current (A)
resistance (Ohms)

Question 14

Potential difference (in terms of resistance)

Answer 14

V = IR

potential difference (volts)
current (A)
resistance (Ohms)

Question 15

Resistance (in terms of resistivity)

Answer 15

R = ρL / A

resistance (Ohms)
resistivity (Ωm⁻¹)
length (m)
cross-sectional area (m²)

Question 16

Density

Answer 16

ρ = m/V

density (kgm⁻³)
mass (kg)
volume (m³)

Question 17

Pressure (in terms of area)

Answer 17

P = F/A

pressure (Pa/Nm⁻²)
force (N)
cross-sectional area (m²)

Question 18

Spring constant

Answer 18

F = kx

force (N)
spring constant
x (m)

Question 19

Kinematics equations not given

Answer 19

v = u + at
s = { (u+v)/2 } x t

Question 20

Net force in terms of momentum

Answer 20

Fₙ = ∆mv / ∆t or
= ∆p / ∆t

Net force (N)
change in momentum (kg•m/s)
time (s)

Question 21

Momentum

Answer 21

p = mv

momentum (kgm⁻¹)
mass (kg)
velocity (ms⁻¹)

Question 22

Impulse

Answer 22

Fₙ = (mv - mu)/t

∆momentum (p) = Fₙ x ∆t

Question 23

Elastic force

Answer 23

F = -kx

force (N)
spring constant
x (m)

Question 24

Weight

Answer 24

F = mg

force (N)
mass (kg)
gravitational acceleration (ms⁻²)

Question 25

Torque (moment) | Torque (torque)

Answer 25

``` τ = F⊥ x r or τ = F x r⊥ or τ = Fr sinθ or τ = 2Fr ``` torque (Nm) either perpendicular force (N) or perpendicular distance from pivot (m)

Question 26

Efficiency ratio

Answer 26

useful energy output / total energy supplied

Question 27

Net pressure (pressure at the bottom of a not fully submerged mass)

Answer 27

Pₙ = Pₒ + ϱg∆h ``` pressure (Pa/Nm⁻²) atmospheric pressure (101,000Pa) density (kgm⁻³) gravitational acceleration (ms⁻²) height (m) ```

Question 28

Buoyancy formula

Answer 28

B = ϱg∆h•A or ϱgV ``` buoyancy (N) density (kgm⁻³) gravitational acceleration (ms⁻²) height (m) area (m²) ```

Question 29

Archimedes principle (applied formula)

Answer 29

∆p = p₂ - p₁ = ϱg(h₂ - h₁)

Question 30

Stress

Answer 30

σ = F/A stress (Pa/Nm⁻²) force (N) area (m²)

Question 31

Strain

Answer 31

ε = x/L strain (no unit) extension (m) length (m)

Question 32

Young's modulus

Answer 32

E = σ / ε or E = FL / Ax Young's modulus (Pa/Nm⁻²) stress (Pa/Nm⁻²) strain (no unit)

Question 33

Hooke's Law in series

Answer 33

kᴛᴏᴛᴀʟ = (1/k1 + 1/k2 + 1/k3)⁻¹

Question 34

Hooke's Law in parallel

Answer 34

kᴛᴏᴛᴀʟ = k1 + k2 + k3

Question 35

Velocity

Answer 35

V = ∆d / ∆t velocity (ms⁻¹) displacement (m) time (s)

Question 36

Acceleration

Answer 36

a = ∆v / ∆t (area under graph is displacement) acceleration (ms⁻²) velocity (ms⁻¹) time (s)

Question 37

Elastic potential energy

Answer 37

Eₚ = 1/2 kx² elastic potential energy (J) spring constant extension (m)

Question 38

Elastic modulus

Answer 38

σε = energy / Volume stress•strain (Pa/Nm⁻²) energy (J) Volume (m³)

Question 39

Base Quantities and Units

Answer 39

``` Time (s) Mass (kg) Distance (m) Amount of substance (mol) Current (A) Temperature (K) ```

Question 40

Newton's first law of motion

Answer 40

an object will remain at rest or in a state of motion unless it is acted upon by a resultant force

Question 41

Newton's second law of motion

Answer 41

resultant force is proportional to rate change of momentum

Question 42

Newton's third law of motion

Answer 42

when 2 bodies interact, the forces they exert on each other are equal and opposite in size

Question 43

Principle of conservation of momentum

Answer 43

in an isolated system, the total momentum of the masses before collision is equal to the total momentum of the masses after collision

Question 44

Elastic Collisions

Answer 44

KE is conserved and rsa is equal to rss

Question 45

Inelastic Collisions

Answer 45

KE after collision is lesser than KE before collision

Question 46

Principle of moments

Answer 46

when in equilibrium, total clockwise moment about a point is equal to the total anticlockwise moment about that point

Question 47

Conditions of equilibrium

Answer 47

sum of all force is equal to zero and sum of all clockwise moments is equal to the sum of all anticlockwise moments, there is no net force or resultant force

Question 48

Principle of conservation of energy

Answer 48

Energy cannot be created or destroyed, only transformed

Question 49

Archimedes' Principle

Answer 49

Mass of a body submerged is equal to the mass of water it displaced

Question 50

Wave period

Answer 50

T = 1/f time (s) frequency (Hz)